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SMTP command-line test tool

swaks (Swiss Army Knife SMTP) is a command-line tool written in Perl
for testing SMTP setups; it supports STARTTLS and SMTP AUTH (PLAIN,
LOGIN, CRAM-MD5, SPA, and DIGEST-MD5). swaks allows one to stop the
SMTP dialog at any stage, e.g to check RCPT TO: without actually
sending a mail.

If you are spending too much time iterating "telnet foo.example 25"
swaks is for you.